| Description |
We propose to use Herschel PACS photometry observations at 70 and 160 microns to study the global structure of protoplanetary disks in different stages of evolution. Our goal is to determine the contribution of the various physical disk dispersal mechanisms (grain growth/settling, planet formation, photoevaporation) for a uniform sample of disks withdifferent ages and stellar masses. Far-IR observations are extremelysensitive to the global disk properties (flaring, small dust graindepletion, total disk mass). The data will constrain the diskstructure as well as the way evolution proceeds (inside-out evolutionversus homologous depletion), revealing the effects of the different dispersal mechanisms and their interplay depending on the age and mass of the systems. We will study a large sample of disks in the Cep OB2 region, which contains three populations with ages 1, 4, and 12 Myr. Cep OB2 has been extensively studied at optical and IR(Spitzer) wavelengths, so the properties of these stars and their inner disks (including the presence of gas and accretion)have been determined. Millimeter observations are also available for 32 objects. The sample contains 59 disks (observed with IRS) plus virgul120additional cluster members for which we have optical, IRAC and MIPS data. The disks span a wide range of SED types, from flared, primordial disks with small grains to flattened objects without silicate features and transition objects with cleared or optically thin inner disks, and also show differences in the gas content and accretion. By combining the PACS photometry with our available multiwavelength data and our RADMC radiative transfer code for disk modeling, we willbe able to trace the global disk structure/dust content of the objects. We will then examine the global trends of disk structureand evolutionary status within the full sample, checking its dependencyof age and stellar mass in order to understand the effect of the differentphysical processes on disk dispersal. |
